Ruthenium-based carbon dioxide hydrogenation catalyst based on MoS2 and preparation method and application thereof

Abstract

The invention provides a ruthenium-based carbon dioxide hydrogenation catalyst based on MoS2 as well as a preparation method and application of the ruthenium-based carbon dioxide hydrogenation catalyst. The carbon dioxide hydrogenation catalyst comprises silicon dioxide, ruthenium and molybdenum disulfide, and the ruthenium and the molybdenum disulfide are loaded on the silicon dioxide. Therefore, in the carbon dioxide hydrogenation catalyst, the molybdenum disulfide is used as an auxiliary agent, so that the generation of methane (CH4) can be remarkably inhibited while a high CO2 conversion rate is maintained, the reversion of a product from CH4 leading to carbon monoxide (CO) leading is realized, and the inherent core defects that an existing Ru-based CO2 hydrogenation catalyst is too high in methanation activity, low in CO selectivity and difficult to consider activity-selectivity at the same time are overcome.

Description

Technical Field

[0001] This invention relates to the field of materials technology, specifically to carbon dioxide hydrogenation catalysts, their preparation methods, and applications. Background Technology

[0002] Using green hydrogen (H2) generated from renewable energy to catalytically hydrogenate CO2 into high-value-added chemicals or fuels (such as syngas, methanol, and low-carbon olefins) is one of the important ways to achieve CO2 recycling. Among the many conversion pathways, the direct production of syngas from CO2 hydrogenation (CO + H2, i.e., reverse water-gas shift reaction, RWGS: CO2 + H2 → CO + H2O) has broad prospects because its products are important basic chemical raw materials.

[0003] Ruthenium (Ru)-based catalysts have attracted much attention due to their high activity in CO2 hydrogenation. However, traditional Ru-based catalysts suffer from a significant technical drawback: their inherently high methanation activity. In CO2 hydrogenation, Ru tends to undergo deep hydrogenation, primarily converting CO2 to methane (CH4) rather than the desired carbon monoxide (CO). This characteristic severely limits the application of Ru-based catalysts in the selective production of syngas (especially with high CO selectivity). Although the RWGS reaction thermodynamically favors CO production, the strong dissociation and adsorption capacity of the Ru catalyst surface often leads to deep hydrogenation of intermediate species to CH4, making CH4 the dominant product and resulting in low CO selectivity, i.e., a low CO formation rate. Summary of the Invention The purpose of this invention is to at least partially solve one of the technical problems in the related art. To this end, one object of this invention is to provide a carbon dioxide hydrogenation catalyst that can improve the selectivity of carbon monoxide in the catalytic hydrogenation of carbon dioxide to syngas.

[0004] In one aspect, the present invention provides a carbon dioxide hydrogenation catalyst. According to embodiments of the present invention, the carbon dioxide hydrogenation catalyst comprises silica, ruthenium, and molybdenum disulfide, wherein the ruthenium and the molybdenum disulfide are supported on the silica. Thus, in this carbon dioxide hydrogenation catalyst, molybdenum disulfide, as a promoter, can significantly suppress the formation of methane (CH4) while maintaining a high CO2 conversion rate, achieving a reversal of the product dominance from CH4 to carbon monoxide (CO), thereby overcoming the core defects inherent in existing Ru-based CO2 hydrogenation catalysts, such as excessively high methanation activity, low CO selectivity, and difficulty in achieving a balance between activity and selectivity.

[0005] According to an embodiment of the present invention, based on the total mass of the carbon dioxide hydrogenation catalyst, the carbon dioxide hydrogenation catalyst comprises, by mass percentage: 85% to 99% of the silicon dioxide; 0.01% to 10% of the ruthenium; and 0.01% to 5% of the molybdenum disulfide.

[0006] According to an embodiment of the present invention, the carbon dioxide hydrogenation catalyst comprises 0.1% to 1% of the molybdenum disulfide.

[0007] In another aspect of the present invention, a method for preparing the aforementioned carbon dioxide hydrogenation catalyst is provided. According to an embodiment of the present invention, the method for preparing the carbon dioxide hydrogenation catalyst includes: preparing a two-dimensional molybdenum disulfide dispersion; loading the two-dimensional molybdenum disulfide dispersion onto a silica support, subjecting it to a first drying treatment to obtain a MoS2-SiO2 support; loading a ruthenium salt solution onto the MoS2-SiO2 support, subjecting it to a second drying treatment to obtain a ruthenium salt-MoS2-SiO2 support; and reducing the ruthenium salt-MoS2-SiO2 support with ruthenium to obtain the carbon dioxide hydrogenation catalyst. Thus, the prepared carbon dioxide hydrogenation catalyst contains the promoter molybdenum disulfide, which can significantly inhibit the formation of methane (CH4) while maintaining a high CO2 conversion rate, achieving a reversal of the product from CH4-dominated to carbon monoxide (CO-dominated), solving the core defects of existing Ru-based CO2 hydrogenation catalysts, such as excessively high methanation activity, low CO selectivity, and difficulty in achieving a balance between activity and selectivity; moreover, the above preparation method is simple and effective, easy to implement and industrially mass-produced.

[0008] According to an embodiment of the present invention, a method for preparing the two-dimensional molybdenum disulfide dispersion includes: dispersing molybdenum disulfide nanosheets in a solvent and stirring until uniform to obtain a preliminary dispersion; centrifuging the preliminary dispersion at a first rotation speed for a certain time to obtain a supernatant; and centrifuging the supernatant at a second rotation speed for a certain time to obtain the two-dimensional molybdenum disulfide dispersion, wherein the second rotation speed is greater than the first rotation speed.

[0009] According to embodiments of the present invention, the two-dimensional molybdenum disulfide dispersion is loaded onto the silica support by an equal-volume impregnation method; and / or, the ruthenium salt solution is loaded onto the MoS2-SiO2 support by an equal-volume impregnation method.

[0010] According to an embodiment of the present invention, the concentration of the ruthenium salt is 0.1~30 mmol / L.

[0011] According to an embodiment of the present invention, the first rotational speed is 1000~3000 rpm, and / or the second rotational speed is 2000~6000 rpm.

[0012] According to an embodiment of the present invention, the first drying condition is vacuum drying at 60~80°C.

[0013] In another aspect, the present invention provides an application of the aforementioned carbon dioxide hydrogenation catalyst in the catalytic preparation of syngas via carbon dioxide hydrogenation. Thus, in the catalytic reaction, while maintaining a high CO2 conversion rate, the formation of methane (CH4) can be significantly suppressed, achieving a reversal of the product dominance from CH4 to carbon monoxide (CO). In other words, in the catalytic preparation of syngas via carbon dioxide hydrogenation, not only is a high carbon dioxide conversion rate guaranteed, but the selectivity of carbon monoxide is also improved.

[0014] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0015] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a flowchart of a method for preparing a carbon dioxide hydrogenation catalyst in one embodiment of the present invention; Figure 2 This is a flowchart of a method for preparing a carbon dioxide hydrogenation catalyst in another embodiment of the present invention. Detailed Implementation

[0016] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0017] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0018] In one aspect, the present invention provides a carbon dioxide hydrogenation catalyst. According to embodiments of the present invention, the carbon dioxide hydrogenation catalyst comprises silica, ruthenium, and molybdenum disulfide, with ruthenium and molybdenum disulfide supported on silica. Thus, in this carbon dioxide hydrogenation catalyst, molybdenum disulfide acts as a promoter, significantly inhibiting methane (CH4) formation while maintaining high CO2 conversion, achieving a reversal of the product dominance from CH4 to carbon monoxide (CO), thereby overcoming the core defects inherent in existing Ru-based CO2 hydrogenation catalysts, such as excessively high methanation activity, low CO selectivity, and difficulty in achieving a balance between activity and selectivity.

[0019] According to some embodiments of the present invention, based on the total mass of the carbon dioxide hydrogenation catalyst, the carbon dioxide hydrogenation catalyst comprises, by mass percentage: 85%~99% (e.g., 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, etc.) silicon dioxide; and 0.01%~10% (e.g., 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.5%). Ruthenium in the range of 2.6%, 2.8%, 3.0%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, etc.; and molybdenum disulfide in the range of 0.01% to 5% (e.g., 0.01%, 0.03%, 0.05%, 0.08%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.5%, 2.6%, 2.8%, 3.0%, 3.5%, 4%, 4.5%, 5%, etc.). Therefore, the carbon dioxide hydrogenation catalyst with the above ratio can effectively catalyze the hydrogenation of carbon dioxide to produce syngas. In this catalytic reaction, it can effectively ensure a high conversion rate of carbon dioxide, while improving the selectivity of carbon monoxide production and inhibiting the formation of methane.

[0020] According to some embodiments of the present invention, the carbon dioxide hydrogenation catalyst comprises 0.1% to 1% molybdenum disulfide. Therefore, by adding trace amounts of molybdenum disulfide, the selectivity for carbon monoxide formation can be significantly improved, while methane formation can be suppressed; and the addition of trace amounts of molybdenum disulfide does not significantly increase raw material costs.

[0021] According to some embodiments of the present invention, molybdenum disulfide can be a conventional molybdenum disulfide material (i.e., non-defective molybdenum disulfide) or a molybdenum disulfide material containing defects (i.e., atomic-level incompleteness or structural anomalies exist in the crystal structure of molybdenum disulfide (MoS2) nanosheets), such as the lack of Mo atoms (Mo vacancies) or S atoms (S vacancies) in the molybdenum disulfide crystal.

[0022] According to some embodiments of the present invention, molybdenum disulfide can be loaded onto a silicon dioxide surface in the form of nanosheets.

[0023] In another aspect of the invention, the invention provides a method for preparing the aforementioned carbon dioxide hydrogenation catalyst. According to an embodiment of the invention, referring to… Figure 1Methods for preparing carbon dioxide hydrogenation catalysts include: S100: Preparation of two-dimensional molybdenum disulfide (2D-MoS2) dispersion; According to some embodiments of the present invention, a method for preparing a two-dimensional molybdenum disulfide dispersion includes: S110: Molybdenum disulfide nanosheets are dispersed in a solvent and stirred until homogeneous to obtain a preliminary dispersion.

[0024] In some embodiments, molybdenum disulfide nanosheets can be conventional molybdenum disulfide materials (i.e., non-defective molybdenum disulfide) or molybdenum disulfide materials containing defects (i.e., atomic-level incompleteness or structural anomalies in the crystal structure of molybdenum disulfide (MoS2) nanosheets), such as the lack of Mo atoms (Mo vacancies) or S atoms (S vacancies) in the molybdenum disulfide crystal.

[0025] In some embodiments, the solvent may be an organic solvent, such as isopropanol.

[0026] In some embodiments, after dispersing molybdenum disulfide nanosheets in a solvent, a preliminary dispersion of molybdenum disulfide nanosheets can be obtained by vigorous stirring and ultrasonic treatment for 0.5 to 8 hours, thereby avoiding the stacking of molybdenum disulfide nanosheets.

[0027] S120: After centrifuging the preliminary dispersion at the first speed for a certain period of time, the supernatant is obtained.

[0028] In some embodiments, the first rotational speed can be 1000~3000rpm, such as 1000rpm, 1200rpm, 1400rpm, 1500rpm, 1600rpm, 1800rpm, 2000rpm, 2200rpm, 2400rpm, 2500rpm, 2600rpm, 2800rpm, 3000rpm, etc.

[0029] In some embodiments, the above steps may involve centrifugation at a first rotational speed for 5 to 30 minutes.

[0030] S130: Centrifuge the supernatant at a second rotation speed for a certain time to obtain a two-dimensional molybdenum disulfide (2D-MoS2) dispersion. The second rotation speed is greater than the first rotation speed.

[0031] In some embodiments, the second rotational speed is 2000~6000 rpm, such as 2000 rpm, 2300 rpm, 2500 rpm, 2800 rpm, 3000 rpm, 3200 rpm, 3500 rpm, 3800 rpm, 4000 rpm, 4200 rpm, 4500 rpm, 4800 rpm, 5000 rpm, 5200 rpm, 5500 rpm, 5800 rpm, 6000 rpm, etc. The second rotational speed is greater than the first rotational speed. Through two-step gradient centrifugation purification, it can help obtain a dispersion of monolayer or few-layer molybdenum disulfide nanosheets, avoiding the stacking of molybdenum disulfide nanosheets. This helps improve the uniformity of molybdenum disulfide loading on the silica surface, thereby contributing to improved catalytic efficiency.

[0032] According to some embodiments of the present invention, the concentration of molybdenum disulfide in the molybdenum disulfide dispersion can be 1% to 99%, specifically, it can be 10% to 80%, and more specifically, it can be 20% to 50%.

[0033] S200: A two-dimensional molybdenum disulfide dispersion is loaded onto a silica support and subjected to a first drying treatment to obtain a MoS2-SiO2 support.

[0034] In some embodiments, a two-dimensional molybdenum disulfide dispersion is loaded onto a silica support by an equal-volume impregnation method, followed by drying to remove the solvent, thereby achieving the loading of molybdenum disulfide onto the silica support. This results in a high loading rate of molybdenum disulfide on the support and is easy to implement.

[0035] In some embodiments, when loading is performed using the equal-volume impregnation method, the ratio of the volume of the two-dimensional molybdenum disulfide dispersion to the mass of silica is (10~160) mL: 5 g.

[0036] In some embodiments, the first drying conditions are vacuum drying at 60~80°C (e.g., 60°C, 65°C, 70°C, 75°C, 80°C, etc.).

[0037] S300: Load ruthenium salt solution onto MoS2-SiO2 support, followed by a second drying treatment to obtain ruthenium salt-MoS2-SiO2 support; In some embodiments, ruthenium salt solution is loaded onto a MoS2-SiO2 support using an equal-volume impregnation method. This results in a high loading rate of ruthenium salt on the MoS2-SiO2 support and is easy to implement. Furthermore, the distributed impregnation of molybdenum disulfide and ruthenium salt, with a preference for impregnating molybdenum disulfide, contributes to the dispersion and uniformity of the ruthenium loading, thereby effectively suppressing sintering deflaking of the catalyst during the catalytic hydrogenation of carbon dioxide to syngas. For example, compared to simultaneous impregnation of ruthenium and molybdenum disulfide, the distributed impregnation loading of this invention can improve ruthenium dispersion by 40%.

[0038] In some embodiments, the concentration of ruthenium salt is 0.1–30 mmol / L, for example, 0.1 mmol / L, 0.5 mmol / L, 1 mmol / L, 2 mmol / L, 3 mmol / L, 5 mmol / L, 8 mmol / L, 10 mmol / L, 12 mmol / L, 15 mmol / L, 14 mmol / L, 16 mmol / L, 18 mmol / L, 20 mmol / L, 22 mmol / L, 25 mmol / L, 28 mmol / L, 30 mmol / L, etc. This facilitates the preparation of molybdenum disulfide with a loading of 0.01%–5%.

[0039] In some embodiments, the ruthenium salt may be ruthenium nitrate, ruthenium chloride, ruthenium acetate, or ruthenium nitrite nitrate (Ru(NO)(NO3)). x (OH) y At least one of (x+y=3).

[0040] In some embodiments, the second drying conditions are vacuum drying at 60~80°C (e.g., 60°C, 65°C, 70°C, 75°C, 80°C, etc.).

[0041] According to some embodiments of the present invention, in the above preparation process, the amount of molybdenum disulfide, the amount of ruthenium salt, the amount of silicon dioxide, etc., are all based on the above requirements for the content of each component in the carbon dioxide hydrogenation catalyst of the product, that is, the carbon dioxide hydrogenation catalyst prepared includes: 85%~99% silicon dioxide; 0.01%~10% ruthenium; and 0.01%~5% molybdenum disulfide.

[0042] S400: Ruthenium reduction of ruthenium salt-MoS2-SiO2 support yields carbon dioxide hydrogenation catalyst, namely Ru-MoS2-SiO2 catalyst.

[0043] In some embodiments, ruthenium can be reduced by hydrogen, for example, by reducing ruthenium to elemental metal using a mixture of hydrogen and nitrogen; specifically: the initial temperature can be 400~500℃, the pressure is atmospheric pressure, the reducing gas is H2, and the reduction time is 1~3h.

[0044] According to embodiments of the present invention, the prepared carbon dioxide hydrogenation catalyst contains molybdenum disulfide as an auxiliary agent, which can significantly inhibit the formation of methane (CH4) while maintaining a high CO2 conversion rate, thereby reversing the product from CH4-dominated to carbon monoxide (CO-dominated)-dominated, solving the core defects of existing Ru-based CO2 hydrogenation catalysts, such as excessively high methanation activity, low CO selectivity, and difficulty in achieving a balance between activity and selectivity; moreover, the above preparation method is simple and effective, and easy to implement and industrialize.

[0045] In another aspect, the present invention provides an application of the aforementioned carbon dioxide hydrogenation catalyst in the catalytic preparation of syngas via carbon dioxide hydrogenation. Thus, in the catalytic reaction, while maintaining a high CO2 conversion rate, the formation of methane (CH4) can be significantly suppressed, achieving a reversal of the product dominance from CH4 to carbon monoxide (CO). In other words, in the catalytic preparation of syngas via carbon dioxide hydrogenation, not only is a high carbon dioxide conversion rate guaranteed, but the selectivity of carbon monoxide is also improved.

[0046] According to some embodiments of the present invention, the conditions and methods for catalytically preparing syngas by carbon dioxide hydrogenation include: using a mixture of CO2 + H2 / N2 as the reactant gas, reacting it in a fixed-bed reactor equipped with the carbon dioxide hydrogenation catalyst described above, at a reaction temperature of 300~600°C, at a reaction pressure of atmospheric pressure, and at a reaction volume hourly space velocity (GHSV) of 25000 h⁻¹. -1 CO product is collected at the reactor outlet. The reaction volume hourly space velocity (GHSV) is defined as the volumetric flow rate of the gaseous feedstock (based) entering the reaction system per hour divided by the volume of the catalyst, expressed as GHSV, with units of h⁻¹. -1 .

[0047] In some embodiments, the reaction gas is a CO2 + H2 / N2 mixture with a molar ratio of CO2:H2 = 1:1, and the volume fraction of N2 in the mixture is 33%.

[0048] In some embodiments, in the above-described reaction of catalytic hydrogenation of carbon dioxide to produce syngas, the selectivity of carbon monoxide in the product is 60% or more, for example, up to 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc.

[0049] According to some embodiments of the present invention, since the reaction for the catalytic production of syngas from carbon dioxide hydrogenation includes hydrogen gas, the ruthenium salt-MoS2-SiO2 support prepared in step S300 can be directly placed in a fixed-bed reactor for in-situ reduction during the preparation of the carbon dioxide hydrogenation catalyst. That is, ruthenium can be reduced first in the reactor, and after reduction, the reactor temperature and gas flow rate can be adjusted. Once stable, the catalytic reaction to produce syngas can continue. This simplifies the process and improves production efficiency.

[0050] Example Example 1 0.24 g of defective MoS2 nanosheets were added to 80 mL of isopropanol aqueous solution, stirred vigorously and sonicated to obtain a preliminary dispersion. Centrifuge the initial dispersion at 1500 rpm for 10 minutes or collect the supernatant. The supernatant was centrifuged at 4000 rpm for 10 minutes to remove the precipitate and collect the supernatant (2D-MoS2) to obtain a 2D-MoS2 dispersion. 80 mL of the 2D-MoS2 dispersion prepared above was impregnated onto 5 g of SiO2 support using the equal volume impregnation method, and then dried under vacuum at 80 °C to obtain the MoS2-SiO2 support. 12.5 ml of 8 mmol / L ruthenium chloride solution was impregnated onto the MoS2-SiO2 support using the equal volume impregnation method, and then dried to obtain the ruthenium salt-MoS2-SiO2 support. By reducing the ruthenium salt-MoS2-SiO2 support with hydrogen, a carbon dioxide hydrogenation catalyst, namely the Ru-MoS2-SiO2 catalyst, is obtained.

[0051] Example 2 0.24 g of defective MoS2 nanosheets were added to 80 mL of isopropanol solution, stirred vigorously and sonicated to obtain a preliminary dispersion. Centrifuge the initial dispersion at 1500 rpm for 10 minutes or collect the supernatant. The supernatant was centrifuged at 4000 rpm for 10 minutes to remove the precipitate and collect the supernatant (2D-MoS2) to obtain a 2D-MoS2 dispersion. 80 mL of the 2D-MoS2 dispersion prepared above was impregnated onto 5 g of SiO2 support using the equal volume impregnation method, and then dried under vacuum at 80 °C to obtain the MoS2-SiO2 support. A 6.25 ml solution of 8 mmol / L ruthenium nitrate was impregnated onto a MoS2-SiO2 support using an equal-volume impregnation method, and then dried to obtain a ruthenium salt-MoS2-SiO2 support. By reducing the ruthenium salt-MoS2-SiO2 support with hydrogen, a carbon dioxide hydrogenation catalyst, namely the Ru-MoS2-SiO2 catalyst, is obtained.

[0052] Example 3 0.24 g of defective MoS2 nanosheets were added to 80 mL of isopropanol solution, stirred vigorously and sonicated to obtain a preliminary dispersion. Centrifuge the initial dispersion at 1500 rpm for 10 minutes or collect the supernatant. The supernatant was centrifuged at 4000 rpm for 10 minutes to remove the precipitate and collect the supernatant (2D-MoS2) to obtain a 2D-MoS2 dispersion. Repeat the above steps once to obtain another 2D-MoS2 dispersion; Two × 80 mL of the 2D-MoS2 dispersion prepared above was impregnated onto 5 g of SiO2 support using the equal volume impregnation method, and then dried under vacuum at 80 °C to obtain the MoS2-SiO2 support. The ruthenium salt-MoS2-SiO2 support was obtained by impregnating 6.25 ml of 8 mmol / L ruthenium acetate solution onto the MoS2-SiO2 support using the equal volume impregnation method and then drying. By reducing the ruthenium salt-MoS2-SiO2 support with hydrogen, a carbon dioxide hydrogenation catalyst, namely the Ru-MoS2-SiO2 catalyst, is obtained.

[0053] Example 4 0.24 g of defective MoS2 nanosheets were added to 80 mL of isopropanol solution, stirred vigorously and sonicated to obtain a preliminary dispersion. Centrifuge the initial dispersion at 1500 rpm for 10 minutes or collect the supernatant. The supernatant was centrifuged at 4000 rpm for 10 minutes to remove the precipitate and collect the supernatant (2D-MoS2) to obtain a 2D-MoS2 dispersion. Repeat the above steps three times to obtain three more 2D-MoS2 dispersions; 4 × 80 mL of the 2D-MoS2 dispersion prepared above was impregnated onto 5 g of SiO2 support using the equal volume impregnation method, and then dried under vacuum at 80 °C to obtain MoS2-SiO2 support; 6.25 ml of ruthenium nitrite (Ru(NO)(NO3)) was impregnated using the equal-volume impregnation method. x (OH) y Ruthenium salt-MoS2-SiO2 support was obtained by impregnating a solution of x+y=3 and 0.15g / LRu onto a MoS2-SiO2 support and drying it. By reducing the ruthenium salt-MoS2-SiO2 support with hydrogen, a carbon dioxide hydrogenation catalyst, namely the Ru-MoS2-SiO2 catalyst, is obtained.

[0054] Example 5 0.24 g of defective MoS2 nanosheets were added to 80 mL of isopropanol solution, stirred vigorously and sonicated to obtain a preliminary dispersion. Centrifuge the initial dispersion at 1500 rpm for 10 minutes or collect the supernatant. The supernatant was centrifuged at 4000 rpm for 10 minutes to remove the precipitate and collect the supernatant (2D-MoS2) to obtain a 2D-MoS2 dispersion. 80 mL of the 2D-MoS2 dispersion prepared above was impregnated onto 5 g of SiO2 support using the equal volume impregnation method, and then dried under vacuum at 80 °C to obtain the MoS2-SiO2 support. A ruthenium salt-MoS2-SiO2 support was obtained by impregnating 62.5 ml of 8 mmol / L ruthenium acetate solution onto a MoS2-SiO2 support using an equal-volume impregnation method and then drying. By reducing the ruthenium salt-MoS2-SiO2 support with hydrogen, a carbon dioxide hydrogenation catalyst, namely the Ru-MoS2-SiO2 catalyst, is obtained.

[0055] Example 6 0.24 g of defective MoS2 nanosheets were added to 80 mL of isopropanol solution, stirred vigorously and sonicated to obtain a preliminary dispersion. Centrifuge the initial dispersion at 1500 rpm for 10 minutes or collect the supernatant. The supernatant was centrifuged at 4000 rpm for 10 minutes to remove the precipitate and collect the supernatant (2D-MoS2) to obtain a 2D-MoS2 dispersion. 80 mL of the 2D-MoS2 dispersion prepared above was impregnated onto 5 g of SiO2 support using the equal volume impregnation method, and then dried under vacuum at 80 °C to obtain the MoS2-SiO2 support. 12.5 ml of 8 mmol / L ruthenium acetate solution was impregnated onto the MoS2-SiO2 support using the equal volume impregnation method, and then dried to obtain the ruthenium salt-MoS2-SiO2 support. By reducing the ruthenium salt-MoS2-SiO2 support with hydrogen, a carbon dioxide hydrogenation catalyst, namely the Ru-MoS2-SiO2 catalyst, is obtained.

[0056] Comparative Example 1 A 12.5 ml solution of 8 mmol / L ruthenium acetate was impregnated onto a SiO2 support using an equal-volume impregnation method, and then dried to obtain a ruthenium salt-SiO2 support. Ru-SiO2 catalyst was obtained by reducing ruthenium salt-SiO2 support with hydrogen gas.

[0057] Comparative Example 2 0.24 g of defective MoS2 nanosheets were added to 80 mL of isopropanol solution, stirred vigorously and sonicated to obtain a preliminary dispersion. Centrifuge the initial dispersion at 1500 rpm for 10 minutes or collect the supernatant. The supernatant was centrifuged at 4000 rpm for 10 minutes to remove the precipitate and collect the supernatant (2D-MoS2) to obtain a 2D-MoS2 dispersion. The 2D-MoS2 dispersion prepared above was impregnated onto 5g of SiO2 support using the equal volume impregnation method, and then dried under vacuum at 80 °C to obtain the MoS2-SiO2 catalyst.

[0058] Comparative Example 3 12.5 ml of 8 mmol / L ruthenium acetate solution was impregnated onto 5 g of molybdenum disulfide powder carrier using the equal volume impregnation method, and then dried to obtain ruthenium salt-MoS2; Ru-MoS2 catalyst was obtained by reducing ruthenium salt-MoS2 with hydrogen gas.

[0059] The component content of the carbon dioxide hydrogenation catalysts obtained in the above examples and comparative examples was tested using an ICP spectrometer. The test results are shown in Table 1.

[0060] Table 1

[0061] The carbon dioxide hydrogenation catalysts obtained in Examples 1-6 and Comparative Examples 1-3 were used to catalyze the preparation of syngas. This included: taking 50 mg of the ruthenium salt-MoS2-SiO2 support prepared in each of the above examples, 50 mg of the ruthenium salt-SiO2 support in Comparative Example 1, 50 mg of the MoS2-SiO2 catalyst in Comparative Example 2, and 50 mg of the ruthenium salt-MoS2 in Comparative Example 3, and placing them into the isothermal zone of a fixed-bed reactor. Before the reaction, the products from Examples 1-6 and Comparative Examples 1 and 3 were subjected to online reduction at 500°C, atmospheric pressure, and H2 as the reducing gas for 2 hours. After reduction, the temperature controller was adjusted to reach the reaction temperature (the above catalytic reaction was carried out three times at reaction temperatures of 300°C, 400°C, and 500°C, respectively), and the flow rate of the mass flow meter was adjusted to 60 mL / min (standard conditions). The reaction was started after the temperature stabilized. After the reaction, the CO2 conversion rate, CO selectivity, and methane CH4 selectivity were tested. The test results are shown in Table 2.

[0062] Table 2

[0063] As can be seen from the data in Table 2, the catalyst of this invention, while maintaining a high carbon dioxide conversion rate, exhibits significantly higher CO selectivity than the comparative Ru-SiO2 catalyst. This indicates that the catalyst of this invention, with only a small amount of molybdenum sulfide added, can achieve a reversal of selectivity from CH4 to CO, demonstrating good reaction stability.

[0064] Although Comparative Examples 2 and 3 showed high selectivity for carbon monoxide, their carbon dioxide conversion rates were low, failing to meet the dual requirements of high carbon dioxide conversion rate and high carbon monoxide selectivity in the catalytic hydrogenation of carbon dioxide to syngas.

[0065] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0066] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0067] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0068] The terms "first" and "second" used in this document are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature marked "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0069] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0070] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A carbon dioxide hydrogenation catalyst, characterized in that, It includes silicon dioxide, ruthenium, and molybdenum disulfide, wherein the ruthenium and the molybdenum disulfide are supported on the silicon dioxide.

2. The carbon dioxide hydrogenation catalyst according to claim 1, characterized in that, Based on the total mass of the carbon dioxide hydrogenation catalyst, by mass percentage, it includes: The silica contains 85% to 99% of the total silica content. The ruthenium content is 0.01% to 10%. 0.01% to 5% of the molybdenum disulfide.

3. The carbon dioxide hydrogenation catalyst according to claim 1, characterized in that, It includes 0.1% to 1% of the molybdenum disulfide.

4. A method for preparing the carbon dioxide hydrogenation catalyst according to any one of claims 1 to 3, characterized in that, include: Preparation of two-dimensional molybdenum disulfide dispersion; The two-dimensional molybdenum disulfide dispersion was loaded onto a silica support and subjected to a first drying treatment to obtain a MoS2-SiO2 support. A ruthenium salt solution was loaded onto the MoS2-SiO2 support, followed by a second drying treatment to obtain the ruthenium salt-MoS2-SiO2 support. The carbon dioxide hydrogenation catalyst was obtained by ruthenium reduction of the ruthenium salt-MoS2-SiO2 support.

5. The method according to claim 4, characterized in that, The method for preparing the two-dimensional molybdenum disulfide dispersion includes: Molybdenum disulfide nanosheets were dispersed in a solvent and stirred until homogeneous to obtain a preliminary dispersion. After centrifuging the preliminary dispersion at a first rotation speed for a certain period of time, the supernatant was obtained. The supernatant is centrifuged at a second rotation speed for a certain time to obtain the two-dimensional molybdenum disulfide dispersion, wherein the second rotation speed is greater than the first rotation speed.

6. The method according to claim 4 or 5, characterized in that, The two-dimensional molybdenum disulfide dispersion was loaded onto the silica carrier by an equal-volume impregnation method. And / or, the ruthenium salt solution is loaded onto the MoS2-SiO2 support by an equal-volume impregnation method.

7. The method according to claim 4 or 5, characterized in that, The concentration of the ruthenium salt is 0.1~30 mmol / L.

8. The method according to claim 5, characterized in that, The first rotational speed is 1000~3000 rpm, and / or the second rotational speed is 2000~6000 rpm.

9. The method according to claim 4, characterized in that, The first drying condition is vacuum drying at 60~80℃.

10. The application of the carbon dioxide hydrogenation catalyst according to any one of claims 1 to 3 in the catalytic preparation of syngas by carbon dioxide hydrogenation.

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